Many electronic instruments such as, for example, a portable oscillographic recorder are provided with openings or slots to receive removable electronic components containing specialized electrical circuitry. In the case of an oscillographic recorder, such components may be a recorder preamplifier module, which is generally rectangular in shape and typically include a front panel at one end thereof which is to be exposed on the control face of the host recorder and a multi-pin connector on the other end thereof for electrical engagement with a mating connector within the recorder.
It has been known to mount such modules to the oscillographic recorder by means of a threaded fastener extending through a tab or flange provided on the front panel of the module. In this respect, the threaded fastener extends through the tab or flange on the front panel and is received within a threaded opening in a bracket or support within the recorder. With such a configuration, the module is inserted into the recorder until the connector thereon engages the connector within the recorder and the threaded fastener is used to secure the module in place. Typically, with such arrangements, the threaded fastener must be completely removed from the module and recorder to remove the module from the instrument.
Another arrangement for mounting modules to an oscillographic recorder of similar electrical instruments comprises a spring loaded latch mounted to the recorder which is operable to engage a tab projecting outward from the surface of the module to lock it in place against a biasing force acting against the module. In this respect, biasing springs are typically provided above and below the connector within the recorder to engage the back panel of the module and to force the module in an electrically non-engaging direction. The tab on the module is positioned so as to engage the latch wherein the module is confined between the latch and the biasing springs. In other words, the module is inserted into the recorder against the biasing force of the springs within the recorder and when such springs have been compressed a sufficient amount, the latching element engages the tab on the surface of the module to retain same within the recorder.
A problem with such an arrangement, however, is that the biasing springs on the recorder tend to force the module and the connector thereon away from the connector mounted within the recorder i.e. out of electrical engagement. More importantly, when inserting the module into the recorder, sufficient force must be exerted on the module to overcome the opposed biasing force of the biasing springs so as to enable the latch on the front face of the recorder to catch the upward projecting tab on the module. In this respect, damage to the connecting pins on the connector can occur as a result of the force necessary in overcoming the forces of the biasing spring.
The present invention overcomes these problems by providing a locking assembly for releasably mounting an electronic module to a host instrument, which locking assembly may be permanently mounted to the host instrument and which fixedly positions modules with the host instrument and gradually moves the electronic module into and out of electrical engagement with the host instrument.